[PATCH 4/5] Powerpc/hw-breakpoint: Optimize disable path

From: Ravi Bangoria
Date: Tue Jun 18 2019 - 00:33:00 EST


Directly setting dawr and dawrx with 0 should be enough to
disable watchpoint. No need to reset individual bits in
variable and then set in hw.

Signed-off-by: Ravi Bangoria <ravi.bangoria@xxxxxxxxxxxxx>
---
arch/powerpc/include/asm/hw_breakpoint.h | 3 ++-
arch/powerpc/kernel/process.c | 12 ++++++++++++
2 files changed, 14 insertions(+), 1 deletion(-)

diff --git a/arch/powerpc/include/asm/hw_breakpoint.h b/arch/powerpc/include/asm/hw_breakpoint.h
index 78202d5fb13a..8acbbdd4a2d5 100644
--- a/arch/powerpc/include/asm/hw_breakpoint.h
+++ b/arch/powerpc/include/asm/hw_breakpoint.h
@@ -19,6 +19,7 @@ struct arch_hw_breakpoint {
/* Note: Don't change the the first 6 bits below as they are in the same order
* as the dabr and dabrx.
*/
+#define HW_BRK_TYPE_DISABLE 0x00
#define HW_BRK_TYPE_READ 0x01
#define HW_BRK_TYPE_WRITE 0x02
#define HW_BRK_TYPE_TRANSLATE 0x04
@@ -68,7 +69,7 @@ static inline void hw_breakpoint_disable(void)
struct arch_hw_breakpoint brk;

brk.address = 0;
- brk.type = 0;
+ brk.type = HW_BRK_TYPE_DISABLE;
brk.len = 0;
if (ppc_breakpoint_available())
__set_breakpoint(&brk);
diff --git a/arch/powerpc/kernel/process.c b/arch/powerpc/kernel/process.c
index f002d2ffff86..265fac9fb3a4 100644
--- a/arch/powerpc/kernel/process.c
+++ b/arch/powerpc/kernel/process.c
@@ -793,10 +793,22 @@ static inline int set_dabr(struct arch_hw_breakpoint *brk)
return __set_dabr(dabr, dabrx);
}

+static int disable_dawr(void)
+{
+ if (ppc_md.set_dawr)
+ return ppc_md.set_dawr(0, 0);
+
+ mtspr(SPRN_DAWRX, 0);
+ return 0;
+}
+
int set_dawr(struct arch_hw_breakpoint *brk)
{
unsigned long dawr, dawrx, mrd;

+ if (brk->type == HW_BRK_TYPE_DISABLE)
+ return disable_dawr();
+
dawr = brk->address;

dawrx = (brk->type & HW_BRK_TYPE_RDWR) << (63 - 58);
--
2.20.1